Encryption-decryption in a four-wave mixing optical arrangement

JOHN FREDY BARRERA; RODRIGO HENAO; MYRIAN TEBALDI; NESTOR BOLOGNINI; ROBERTO TORROBA

Dehradun, Uttaranchal, INDIA

Congreso; International Conference on Optics & Optoelectronics-ICOL-2005; 2005

Instruments Research & Development Establishment (IRDE)

An encryption-decryption station is presented. Encryption is performed using the usual double random phase encoding method. A volume photorefractive BSO crystal is the storing device. An optical system images the encrypted object on the crystal. Information retrieval is done via a phase conjugation operation, under a four-wave mixing optical arrangement. Key to the method is the concept that the encrypted data is codified as a speckle pattern. The volume nature of the speckle recorded information in a photorefractive medium is remarked to emphasize that the reflectivity in phase conjugation plays a major role in the process. It is also interesting to note that for phase conjugation to be improved, the parameters that define the speckle patterns should be optimized. Speckle size is controlled in the proposed optical architecture by varying the optical pupil aperture. Experimental results are presented.